Effect of Livestock Species and Pyrolysis Temperatures on Fertilizer Elements in Biochar Derived from Livestock Manure

Abstract

In this study, we analyzed effect of pyrolysis temperature on fertilizer element concentration in biochar derived from three different livestock manure or compost: hen, broiler, and swine (broiler manure contain bedding litter, and swine compost contain bedding litter and plant wastes for drying). Macronutrients such as phosphate, potassium, and calcium showed an uptrend in nutrient content as the pyrolysis temperature got higher. Phosphate became less soluble at temperature above 600°C due to a decrease in the rate of easy-soluble form while the content of slow-release increased which also reflected in recovery rate of soluble form phosphate. Micronutrient content was different depending on livestock species; hen manure and broiler manure contained high levels of Zn, while swine manure contained high levels of Fe. Available Cu and Zn concentration showed downward trend at 700°C or higher temperature which indicates those elements changed into insoluble form. Wet acid digestion fraction of Zn was also showed downward trend above 700°C which indicates loss of Zn from biochar. Based on the results, manure biochar that has been pyrolyzed at 400-500°C would be good for supplying macronutrients, and that has been pyrolyzed at 400-600°C would be good for supplying micronutrients.